Alarm



July 11, 1939. H. A. GUNION ALARM Filed Dec. 10, 1936 Patented July 11,1939 UNITED STATES PATENT OFFICE ALARM 2 Claims.

This invention relates to burglar and similar alarms and particularly toan alarm device employing a normally open circuit which extends into aprotected area, whereby the alarm will be operated when the circuit iscompleted by an unwarranted or undesired action in that area.

A primary object of the invention is to provide an alarm device ofsimple and compact construction which will give a continuing visible andaudible signal once the portion of the circuit in the protected area hasbeen completed, even though that circuit be immediately broken again.

Another object of the invention is to provide an alarm device which willoperate on an ordinary alternating current source, thereby doing awaywith batteries or transformers usually employed with such devices.

Other objects and advantages of the invention will become apparent fromthe following detailed description and the accompanying drawing, inwhich:

Fig. 1 is a side elevation, partly in section, of an embodiment of theinvention;

Fig. 2- is a sectional View taken on line 2-2 of Fig. 1;

Fig. 3 is an end elevation, partly in section;

Fig. 4 is a diagrammatic view illustrating the circuits employed andwith the operating coil and related mechanism shown in perspective; and

Fig. 5 is a fragmentary perspective view of the insulated pivot supportfor the holding switch member.

The alarm device is housed in a casing Ill mounted on a base II which ispreferably made of insulating material. An L-shaped strip of insulatingmaterial I2 is mounted on the base II, with its shorter end I2 turnedupwardly to form an upstanding panel upon which is mounted a pair ofspaced contact elements I3 and I4. The bracket plate I5 of the tripmechanism overlies the strip I2 and a single set of bolts l6 serves tosecure these parts to the base II. The frame I! of a relay or trip coilI8 is secured, by welding or the like, to the bracket plate [5, and oneend of the plate I5 is formed with spaced ears I9 between which aholding switch member 20 is pivotally mounted for engagement with thecontacts I3 and I4 at one extremity of its pivotal movement.

As best shown in Fig. 5, the lower end of the member 20 is rolled overto form a sleeve for receiving the tube I9a of insulating material, andinsulating bushings I9b are placed on the end of the tube to space theedges of member 20 from the ears I9. A pivot pin I extends through theears I9 and tube 59a to complete the insulated pivotal support formember 26.

The frame I! has upturned arms 2| and 22 between which the coil l8 andits core [8 are seated, and the armature 23 extends over and is.pivotally mounted on the end of arm 2 I. Lateral movement of the fiatplate armature is prevented by ears 24 on the arm 2! that projectthrough notches 25 in the edges of the armature. A relatively stiffspring 26, between the projecting end 21 of the armature 23 and a prong28 struck out from the arm 2i, tends to hold the armature in raisedposition against a stop 29 that may be a central extension of the arm25, Which extension passes through an opening 3i in the armature 23 andis bent to overlie the armature.

The other arm 22 of the frame ll carries an upstanding metal plate 3!which is insulated from the arm by a block of insulating material 32. Acoil spring 33 is mounted between the metal plate 3| and the free end ofthe latch member 20 and tends to force said member into engagement withthe contacts I3 and M.

The switch member 25 is normally latched in off position, Figs. 2 and 3,by the integralhook portion 34 which engages in an opening 35 in thearmature 23. A push button 35 is loosely mounted in the panel forswinging the switch member into this open-circuit position, the pushbutton being alined with an opening 37 in the casing ID for operation bya small rod, such as a pencil.

An electric lamp 38 is mounted in a socket 39 on the base II, and acolored lens ll) is mounted in the front wall of the casing It to give avisual signal when the alarm is energized.

The parts so far described form a unit that may be connected between asource 4! of alternating current, such as the usual volt, 60 cyclealternating current line, and a protective circuit that extends to thearea to be guarded. A switch 42 is included in the connections, beingshown diagrammatically in Fig. i as a single pole, single throw switch,but the switch may be merely a separable plug connector for insertion ina wall socket to connect the alarm system to the power line.

The lamp 38 and trip coil i8 are serially connected between the lead 33and plate 3i by the coil terminals 44, 45, respectively. One wire 46 ofthe protective circuit extends from the plate 31 to a normally openswitch 41 at the area to be protected, and the return wire 48 isconnected to the contact I3 on the insulated strip I2.

The series circuit of these parts is completed to the power source bythe lead 39 that extends from contact E3 to the switch ll.

It will be noted that the spring 33 forms an electrical connectionbetween plate 3| and the switch plate 28, and that the plate 29 andcontact [3 thus form a holding switch in shunt with the switch 4? of theprotective circuit.

An alarm-controlled circuit may be located in the protected area, asindicated by wire 50 that extends from the terminal M to load devices 5|in the protected area, the return wire 52 from such devices beingconnected to the power source lead 43. The nature of the switch 4'! andthe devices 5| will depend upon the purpose of the protective system.

The illustrated embodiment, including the Fig. 4 circuit, isparticularly useful as a burglar alarm for barns, poultry houses andsimilar buildings. The normally open switch 41 may be of any known typehaving means, not shown, for connection to or across doors or windowsfor closing the switch when the door or window is opened. When used as aburglar alarm, the load devices 5| will be lights positioned toilluminate the exterior of the building. When used as a fire alarm, theswitch 4? will be of a known thermal type and the load devices 50 may bethe electrically actuated valves of a sprlinker system.

The apparatus is placed in operation by latching the switch plate 2! tothe armature 23, and closing switch 42. A closure of the switch 41 willthen complete the described series circuit to energize the trip coil [8.The armature 23 is attracted to the coil, thus releasing the plate 2::which engages the contact l3 to complete a holding circuit around theswitch M. The circuit thus remains energized until the button 36 ispressed inwardly to latch the switch plate 20 to the armature 23.

I Due to the alternating current employed and the choice of a relativelystiff spring 26, the armature 23 will vibrate continuously between thestop 29 and the core l8, thus acting as a buzzer to give a continuingaudible signal in addition to the visual signal afforded by the lamp.This action is preferable to the usual make-and-break types of buzzercircuits for a number of reasons.

In the first place, the alarm is very reliable over long periods as theoperation does not depend upon the particular adjustment of vibratorycontacts. Further, the initial cost is decreased by the omission ofvibratory contacts and this, as well as the fool-proof nature of thealarm makes it particularly useful in the protection of outbuildings.The relatively low sound produced by the armature under the joint action.of the stiff spring and the alternating magnetic field is sufficient toawaken the property owner but will not be heard at the protected area,thus giving the property owner the advantage over the thief,particularly when the auxiliary lighting circuit 50- 5Z is not used.

The visual signal afforded by the lamp 3B is of advantage in someinstances, but the primary function of the lamp is that of a resistorwhich limits the voltage drop across the relay coil. The lamp may, forexample, be of the 15 watt, volt type, which has a resistance of about810 ohms. The coil l8 may consist of about 2200 turns of No. 34 wire(0.007 inch diameter), enamel or cotton covered, having a resistance ofabout ohms. The voltage drop across the coil will therefore be about 15volts.

While a preferred embodiment of the invention has been shown anddescribed, it will be understod that various modifications and changesin the details of construction may be resorted to without departing fromthe spirit of the invention within the scope of the appended claims.

I claim:

1. A circuit control device for an alarm system comprising a basemember, a coil frame mounted on said base, a trip coil mounted in saidframe, an armature pivotally mounted on said frame across the end ofsaid coil, a relatively stiif spring tending to move said armature fromsaid coil whereby said armature will be attracted to said coil and willvibrate continuously when said coil is traversed by alternating current,an upstanding panel carried on said base adjacent said coil frame, acontact carried by said panel, an upstanding switch plate pivotallymounted between said frame and said panel, a spring normally biasingsaid switch plate into engagement with said contact, cooperating latchmeans on said armature and said switch plate operative to latch saidswitch plate in a position out of engagement with said contact when saidarmature is away from said coil and said switch plate is tilted out ofengagement with said contact, manually operated means for moving saidswitch plate to latching position against the action of said spring, andan electrical connection between said switch plate and one terminal ofsaid coil; whereby an alarm circuit may be completed by connecting acurrent source between the panel conand the second coil terminal, andconnecting an alarm switch between the first coil terminal and the panelcontact, said switch plate engaging the panel contact on initialenergization of the coil to complete a holding circuit.

2. A circuit control device for an alarm system comprising a basemember, a U-shaped coil frame mounted on said base, a trip coil mountedin said frame, an armature pivotally mounted on one leg of said frameand extending across '=jthe end of said coil, a relatively stiff springtending to move said armature from said coil whereby said armature willbe attracted to said coil and will vibrate continuously when said coilis traversed by alternating current, an upstanding panel mounted on saidbase in spaced relation to the other leg of said coil frame, a contactcarried by said panel, an upstanding switch plate pivotally mountedbetween said frame and said panel having an upper end overlying saidarmature, a spring between said frame and switch plate normally biasingthe latter into engagement with said contact, said spring beinginsulated from said frame, manually operated means for tilting saidswitch plate out of engagement with said contact toward said frame,cooperating latch means on the upper end of said switch plate and saidarmature operative to latch said switch plate in said last mentionedposition when said armature is away from said coil, and an electricalconnection including said spring between said switch plate and oneterminal of said coil, said panel contact and the second coil terminalbeing adapted for connection across a source of alternating currentwhereby an alarm switch may be connected between the panel contact andthe first coil terminal.

HARRY A. GUNION.

